from the manufacturing-architectures dept.
Some Fat Guy writes "There is an interesting paper and Real Video animations on Exponential Assembly here: http://www.zyvex.com/Research/exponential.html The devices described are MEMS devices, but the concept scales down." CP: A more formal journal article from the Foresight Conference is linked to at the end.

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on Friday, January 12th, 2001 at 4:29 PM and is filed under MEMS.
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Presumably the first generation of manipulators would be quite crude, but sufficiently dexterous to assemble better models. The design shown is quite simple and could be made to self- assemble using magnetic fields. It's been done, though not with an actuator on the perpendicular piece yet as far as I know.
There is a story on it at eetimes http://www.eetimes.com/story/technology/OEG20000515S0049 which says :

"The method devised by Liu's team works across the whole chip, with 100 percent yields, by merely applying a linearly increasing magnetic field to the entire substrate after fabrication. The slowly increasing magnetic field causes the 3-D parts to pop up out of the plane of the substrate in the proper order, so that each locks into place before the next pops up. "

I attended the 8th Foresight Conference (Nov-2000, Bethesda) where Zyvex's George Skidmore and Ralph Merkle spoke, respectively premiering the two "rotopod" animations (#31 "Exponentia l assembly"), and speaking on concepts of replication (#32 "Systems issues in the development of nanotechnology").

The Zyvex MEMS exponential assembly scheme is entirely mechanical; no magnetics (as in the cited May-2000 article on Chang Liu/UnivIL-Urbana). It took quite a while (Ralph said after the conference) to develop a workable set of mirrored coordinate systems, so the two assembly planes can operate on each other. In the animation, the process is… hypnotic; a ballet of arms grabbing parts, rotating vertically, then horizontally, as the two platforms provide vertical movement.

The biggest challenge is assembling the first rotopod. They have a meter-scale desktop manipulator, carrying a circuit board, carrying a tiny MEMS gripper (same size/shape as in the unassembled rotopods); the zoom in the animation is vertiginous. A working prototype has been delayed (I learned at the Senior Associates reception) because they need some extra-thick STL, and the one experimentalist with the necessary technique hasn't been too prompt in fulfilling orders.

Their exponential assembly page is dated 8-Jan-2001; despite the Zyvex contingent's enthusiasm at the conference, it seems they took two months to put the animations up; maybe they didn't want press attention too soon. (The publicity trick is to place the Zyvex logo in every frame. <grin>)

As to exponential- vs. self-replication… in his talk, Merkle emphasized that many of the fears/objections to nanotech are based on a biological metaphor of "self-replication". Yes, both living cells and the classic VonNeumann replicating architecture have a "manufacturing element" (computer+manipulator) and an instruction tape. But it's easy enough to abstract the instructions and computers into a single (possibly macroscale) device, and *broadcast* control signals to a legion of manipulators. (With severely circumscribed local control, raw materials must be provided in a strict order.)

With the Zyvex rotopods, the "broadcast" has two components: shared linear motion by the macroscale stages, and rotating-in-unison by the individual assemblers. It's SIMD: single instruction, multiple data (like a parallel computer or square dance). There's no feedback and (at this prototype stage) limited provision for point-failures.

No, it's not "self"-replication like the devices in _Unbounding the Future_, but the broadcast architecture is entirely adequate for many tasks, and safer too; the manufactured devices can't store replication instructions, and if they did and escaped, "the wild" would lack the carefully-arranged feedstock.

I am rather new to Nanodot and I have to say I'm very impressed. However, reports from Zyvex bring up – IMHO – the need for a more focused approach, in parallel to the main (news) site theme. By 'more focused' I mean for example a taxonomy of the milestones and the technologies that are needed to create a working assembler, whether a true nanodevice or in MEMS scale – maintaining an up-to-date FAQ for every subcategory in the site might do the trick in this respect. Also, I would very much want to be able to access a list of related (bottom-up nanotechnology) projects and their timelines – progress in Zyvex being an obvious example, the UNC.edu VR project being another.